Passage channel for a turbomachine and turbomachine

ABSTRACT

A transition duct for a turbomachine, in particular an aircraft engine, for forming a flow channel between an upstream flow cross section and a downstream flow cross section, including supporting ribs which extend between a radially inner duct wall and a radially outer duct wall and each of which has a profile for deflecting a flow from an inlet area to an outlet area of the transition duct, the supporting ribs each having a profile variation in the area of their trailing edge and/or at least one blow-out opening for blowing out a fluid; also disclosed is a turbomachine having a transition duct of this type.

This claims the benefit of European Patent Application EP 12170498.5, filed Jun. 1, 2012 and hereby incorporated by reference herein.

The present invention relates to a transition duct for a turbomachine as well as a turbomachine.

BACKGROUND

A transition or deflecting duct in an axial turbomachine, such as an aircraft engine, conducts a main flow from an upstream flow cross section to a radially offset flow cross section. The transition duct usually has an annular cross section and is situated, for example, between a high pressure turbine and a low pressure turbine (turning mid turbine frame—TMTF). In a three-part design of a turbine, the transition duct may also be situated between a high pressure turbine and an intermediate pressure turbine as well as between the intermediate pressure turbine and a low pressure turbine. In compressors, a transition duct may similarly conduct the flow from an upstream flow cross section to a downstream flow cross section and be situated, for example, between a low pressure compressor and a high pressure compressor.

For reinforcement, a transition duct generally has supporting ribs of the same type distributed over its circumference. The supporting ribs also induce a deflection of the flow, in particular in the circumferential direction, to improve incident flow to the first moving blade row of the downstream turbine or a compressor stage.

The supporting ribs usually have a large relative thickness, i.e., a ratio between profile thickness and chord length and/or a small blade height ratio, i.e., a ratio between blade height and chord length. The comparatively large relative thickness or small relative height of the supporting ribs may be necessary, in particular, for static reasons. However, such a geometry of the supporting ribs results in heavy secondary flows. Edge areas having swirled flow are produced, which may dominate the flow field. Secondary flows of this type have a negative influence on the incident flow of subsequent blades. In particular, they may limit a maximum possible deflection on the hub and housing and result in energy transmission losses. In addition, secondary flows may result in excitations of the first moving blade row of the downstream turbine and thus in high noise development. Moreover, the number of blades of the transition ducts, which is much smaller compared to conventional stator geometries, may cause aerodynamic excitations of the subsequent rotor blades having fundamental modes, so-called engine orders, in the working area of the turbomachine.

A gas turbine which has an annular transition duct, which extends from a high pressure turbine to a low pressure turbine, is known from U.S. 2010/0040462 A1. The transition duct has a radially inner duct wall and a radially outer duct wall, between which stationary blades are situated in the circumferential direction, each of which has a wing profile for deflecting a flow from an inlet area to an outlet area of the transition duct. To minimize a roll-off of the flow in the transition from a horizontal flow to a radially rising flow, the inner lateral surface has a special curvature.

To improve a blade outflow and thus to improve the wake mixture, it is known from EP 2 390 464 A2 to provide turbine-side moving blades with a wave-like profile variation and/or a slot-like outlet opening in the area of their trailing edge for blowing out a fluid for the purpose of improving the incident flow of a subsequent stationary blade row. The blow-out opening may be situated in the flow direction on the camber line or in the trailing edge area on the suction or pressure side.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a transition duct for a turbomachine which eliminates the aforementioned disadvantages and permits an improved wake mixture. A further alternate or additional object of the present invention is to provide a turbomachine which has a high degree of efficiency and a low noise development.

The present invention provides a transition duct for a turbomachine, in particular an aircraft engine, for forming a flow channel between an upstream flow cross section and a downstream flow cross section has supporting ribs which extend between a radially inner duct wall and a radially outer duct wall and which each have a profile for deflecting a flow from an inlet area to an outlet area of the transition duct. According to the present invention, the supporting ribs each have a profile variation and/or at least one blow-out opening for blowing out a fluid in the area of their trailing edge.

The profile variation and/or the at least one blow-out opening induce(s) a passive and/or active wake mixture of the outflow, resulting in a rapid calming of the flow. As a result of the early wake mixture, the inflow of rotor blades downstream from the outlet area of the transition duct is improved, so that energy transmission losses and aerodynamic excitations of the rotor blades are minimized. With the aid of the profile variation or passive wake mixture, a suction-side partial flow and a pressure-side partial flow are equalized with regard to their outflow speed, whereby eddies are reduced when the partial flows merge downstream from the trailing edge, which results in a wake flow which is calmed early on. With the aid of the at least one blow-out opening or active wake mixture, the outflow is energized by blowing in a fluid, which also improves the wake mixture. In addition, the supporting ribs are cooled by the fluid in the area of their trailing edge, which reduces their thermal load. In a combination of the passive and the active wake mixture to form a hybrid-type wake mixture, both equalization and energizing of the outflow take place.

In one exemplary embodiment of a profile variation, the trailing edge is alternately offset in relation to the suction side and in relation to the pressure side. As a result, the trailing edge has a wave shape extending laterally or in the circumferential direction which includes a plurality of wave crests and wave troughs, whereby the trailing edge is enlarged and a suction-side partial flow and a pressure-side partial flow are fanned out. In addition, the partial flows are alternately routed above each other in sections due to the wave shape, viewed in the radial direction, so that not only a “lateral” mixing but also a “radial” mixing takes place. The wave shape is preferably designed to be uniform in such a way that the wave crests and wave troughs have the same suction-side and pressure-side extensions,

In an alternative exemplary embodiment of the profile variation, the trailing edge has a wave-like design, viewed in the flow direction. This provides a plurality of profile truncations (wave troughs) and profile extensions (wave crests), whereby the suction-side partial flow and the pressure-side partial flow each flow away from the trailing edge in sections at an earlier point in time (wave trough) or a later point in time (wave crest), compared to a conventional trailing edge. As a result, a mixed zone is brought forward in sections (wave troughs), and a mixing is initiated at an early stage. The wave shape preferably has a uniform design.

In one exemplary embodiment of an active wake mixture, the at least one blow-out opening exits the trailing edge between the suction side and the pressure side. Due to this measure, the at least one blow-out opening is situated on the camber line of the supporting rib, and the fluid is blown in uniformly between the outflowing partial flows, thereby preventing a deflection of the suction-side or pressure-side partial flow in the circumferential direction.

The at least one blow-out opening is preferably designed as a longitudinal slot, which extends from the inner duct wall to the outer duct wall. In this variant, a suction-side slot area furthermore has a wave-shaped design, and a pressure-side slot area is designed without variation. As a result, the suction-side slot area is enlarged compared to the pressure-side slot area. In addition, the fluid flow is fanned out on the suction side, due to the wave shape.

In addition, a suction-side outflow area opposite the suction-side slot area may be provided with a wave-shaped design. As a result, the suction-side slot area is provided with a profile variation, so that, in combination with the at least one blow-out opening, both a passive and an active wake mixture takes place.

In one exemplary embodiment, in which the at least one blow-out opening is designed as a longitudinal slot which extends from the inner duct wall to the outer duct wall, a pressure-side slot area has a wave shape and a diametrically opposed suction-side slot area is designed without variation. As a result, the pressure-side slot area is enlarged compared to the suction-side slot area. In addition, the fluid flow is fanned out on the pressure side, due to the wave shape.

In addition, a pressure-side outflow area opposite the pressure-side slot area may be provided with a wave-shaped design, so that, in combination with the at least one blow-out opening, both a passive and an active wake mixture takes place.

In one exemplary embodiment, the at least one blow-out opening exits the profile on the suction side. The at least one blow-out opening may be designed as a slot, as a plurality of slots or as a plurality of bore-like openings. The orientation of the at least one blow-out opening and the shape of a downstream trailing edge section are preferably provided in such a way that the so-called “Coanda effect” may be created. In other words, the fluid flow follows the outer contour of the trailing edge section after it is detached therefrom, so that, on the one hand, only a profile-proximate boundary layer is energized by the blow out, and, on the other hand, no cross flows are introduced into the profile-distant layers of the suction-side partial flow.

At least one flow splitter blade may be situated between the supporting ribs, which has a smaller relative profile thickness than the supporting ribs. The at least one flow splitter blade is based on the finding that eddies, flow losses and/or deflection limitations may be reduced if additional deflecting elements are situated between the supporting ribs which are also profiled to deflect the flow, these deflecting elements being designed as narrower and/or shorter flow splitters compared to the supporting ribs.

The flow splitter blades are preferably also provided with a profile variation and/or at least one blow-out opening in the area of their trailing edge, so that a passive and/or active wake mixture of the particular flow splitter blade-side outflow also takes place.

A preferred turbomachine has a transition duct according to the present invention. This transition duct produces an improved inflow from rotor blades downstream from the outlet area of the transition duct, due to the rapid wake mixture. The improved inflow results in minimized energy transmission losses and thus in a high degree of efficiency as well as in a minimized aerodynamic excitation of the downstream rotor blades and thus a noise reduction compared to turbomachines having a conventional transition duct. The transition duct is preferably situated on the turbine side but may also be situated on the compressor side.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the present invention are explained in greater detail below with reference to the highly simplified schematic illustrations.

FIG. 1 shows an axial sectional view and a partial developed view of a transition duct according to one exemplary embodiment of the present invention;

FIG. 2 shows a perspective representation of a supporting rib which has an exemplary trailing edge-side passive wake mixture;

FIG. 3 shows a side view of a supporting rib which has another exemplary trailing edge-side passive wake mixture;

FIG. 4 shows a rearward representation of a supporting rib which has an exemplary active wake mixture;

FIG. 5 shows a rearward representation of a supporting rib which has another exemplary active wake mixture;

FIG. 6 shows a rearward representation of a supporting rib which has an exemplary hybrid wake mixture;

FIG. 7 shows a rearward representation of a supporting rib which has another exemplary hybrid wake mixture;

FIG. 8 shows a cross section of a supporting rib having a lateral blow-out opening as an active wake mixture;

FIG. 9 shows an axial side view and a partial developed view of another exemplary transition duct; and

FIG. 10 shows a developed view of another exemplary embodiment of the transition duct.

DETAILED DESCRIPTION

In the figures, identical structural elements are denoted with the same reference numeral, for the sake of clarity only one element being or may be provided with a reference numeral in the case of multiple identical elements in one figure.

FIG. 1 shows an example of a transition duct 1 between a high pressure turbine 2 and a low-pressure turbine 4 of an axial turbomachine, such as an aircraft engine, in an axial half section or meridian section (upper part of the figure) as well as in a planar developed view or in a profile section (lower part of the figure).

Transition duct 1 is mounted in a stationary manner in a turbine housing, while high pressure turbine 2 and low pressure turbine 4 each have moving blade rows 6 which rotate around a rotation axis or turbine axis R in rotation direction U. Transition duct 1 encompasses rotation axis R and has an annular flow cross section. It has a radially inner duct wall 8, a radially outer duct wall 10 and a high pressure turbine-side inlet area F₁ and a low pressure turbine-side outlet area F₂. As illustrated in FIG. 1, inlet area F₁ is situated radially internally in relation to outlet area F₂, so that a flow 12 flowing through transition duct 1 is guided radially obliquely to the outside in relation to rotation axis R.

It has been found to be advantageous if an axial area ratio of outlet area F₂ to inlet area F₁ is between 2 and 5 (2≦F₂/F₁≦5) and/or if a flow deflection angle Δα=α₁−α₂ is less than 50°.As sketched in FIG. 1, inlet area F₁ and outlet area F₂ are perpendicular to rotation axis R. Flow angle α₁ indicates a deflection angle of an inlet flow 12′ into transition duct 1 to rotation axis R. Flow angle α₂ indicates a deflection angle of an outlet flow 12″ from transition duct 1 to rotation axis R. Flow angles α₁ and α₂ are derived from the mass-averaged axial and circumferential speeds c_(axial) and c_(circumferential) on planes F₁ and F₂ according to a =a +tan (c_(axial)/c_(circumferential)).

For reinforcement, transition duct 1 has a plurality of supporting ribs 14, which extend between inner duct wall 8 and outer duct wall 10 and which are distributed uniformly within transition duct 1, viewed in the circumferential direction. Supporting ribs 14 have a comparatively large relative thickness to achieve their supporting effect and to accommodate supply lines, which are not sketched. In addition, they have a wing-like profile for deflecting flow 12 in the circumferential direction or the rotation direction. In the area of their particular trailing edge 16, they have a wake mixture 18, which is indicated by a circle, in the form of a passive wake mixture 20, (FIGS. 2 and 3), in the form of at least one active wake mixture 22 (FIGS. 4, 5 and 8) or in the form of a combined active and passive wake mixture 20,22 (FIGS. 6 and 7).

A passive wake mixture shown by way of example in FIG. 2 is a trailing edge-side profile variation 20, which is alternately provided in the direction of suction side 24 and in the direction of diametrically opposed pressure side 26. Profile variation 20 thus has a wave shape, which is preferably uniformly designed. Trailing edge 16 has a plurality of lateral wave crests and wave troughs, with the aid of which, on the one hand, the area of suction side 24 and the area of pressure side 26 are enlarged in the trailing edge area. On the other hand, a particular suction-side partial flow and a pressure-side partial flow are fanned out in the area of trailing edge 16, viewed laterally or in the circumferential direction, and alternately guided above each other in sections in the radial direction. As indicated by dashed vertical auxiliary line 27, trailing edge 16 is not axially offset, compared to a conventional straight trailing edge.

An example of a passive wake mixture shown in FIG. 3 is a trailing edge-side profile variation 20 which has a wave-shaped design, viewed in the flow direction. The particular suction-side partial flow and the pressure-side partial flow are fanned out thereby when flowing out in the radial direction, whereby, due to the local profile extensions or profile truncations produced by the wave crests and wave troughs, the suction-side and pressure-side partial flows flow away from particular supporting rib 14 in sections at a later point in time (wave crest) or at an earlier point in time (wave trough), so that the merging of the partial flows is brought forward in time, compared to a conventional trailing edge, which is indicated as dashed auxiliary line 27, viewed in the axial direction or in the flow direction. The wave shape preferably has a uniform design.

FIG. 4 shows an example of an active wake mixture. For this purpose, supporting ribs 14 each have a blow-out opening 22 for blowing out a fluid in the area of their trailing edges 16. Blow-out opening 22 is designed as a longitudinal slot which extends from inner duct wall 8 to outer duct wall 10 (see FIG. 1). Longitudinal slot 22 is located on the camber line of supporting rib 14 and thus splits trailing edge 16 into a suction-side section 28 and a pressure-side section 30. Suction-side section 30 has a suction-side slot area 32 which limits blow-out opening 22, and pressure-side section 28 has a diametrically opposed pressure-side slot area 34 for limiting blow-out opening 22. Suction-side slot area 32 is preferably wave-shaped and provided with a plurality of wave crests and wave troughs. Pressure-side slot area 34 is without variation, and it is straight in the section illustrated. In addition, a suction-side outflow area 36 of suction-side section 28 diametrically opposed to suction-side slot area 32 and a pressure-side outflow area 38 of pressure-side section 30 diametrically opposed to pressure-side slot area 34 are also designed without a contour variation. After flowing around the profile, the suction-side and pressure-side partial flows merge downstream from trailing edge 16, a fluid flow being blown between the partial flows through blow-out opening 22, this fluid flow being laterally fanned out on one side, i.e., on the suction side, by the wave-shaped inner contour of suction-side slot area 32.

FIG. 5 shows another example of an active wake mixture in the area of a trailing edge 16 of supporting ribs 14. In contrast to the preceding example according to FIG. 4, in this exemplary embodiment a pressure-side slot area 34 is wave-shaped and a suction-side slot area 32 is without variation. The other areas forming trailing edge 16, such as a suction-side outflow area 36 and a pressure-side outflow area 38 are also designed without a contour variation in this exemplary embodiment. After flowing around the profile, the suction-side and pressure-side partial flows merge downstream from trailing edge 16, a fluid flow being blown between the partial flows through blow-out opening 22, this fluid flow being laterally fanned out on one side, i.e., on the pressure side, by the wave-shaped inner contour of pressure-side slot area 34.

FIG. 6 shows an example of a combined active and passive, and thus hybrid, wake mixture 20, 22. In addition to the active exemplary embodiment according to FIG. 4, suction-side outflow area 36 in this hybrid exemplary embodiment is also provided with a profile variation 20 and thus not only a suction-side slot area 32. Profile variation 20 is also wave-shaped and designed with a plurality of wave crests and wave troughs. Pressure-side outflow area 38 of pressure-side section 30 is designed without a contour variation. In this hybrid exemplary embodiment, a suction-side partial flow is thus passively fanned out to the side in addition to the suction-side fanning out of the fluid flow. The inner contour and profile variation 20 are preferably positioned in relation to each other in such a way that a wave crest of profile variation 20 is situated in the area of a wave trough of the inner contour and vice versa. Profile variation 20 and the inner contour preferably have an identical design.

FIG. 7 shows another example of a combined active and passive, and thus hybrid, wake mixture 20, 22. In contrast to the hybrid exemplary embodiment according to FIG. 6, pressure-side outflow area 38 in this exemplary embodiment, in addition to the active exemplary embodiment according to FIG. 5, is also provided with a profile variation 20 and thus not only a pressure-side slot area 34. Profile variation 20 is also wave-shaped and provided with a plurality of wave crests and wave troughs. Suction-side outflow area 36 of suction-side section 28 is designed without a contour variation. In this hybrid exemplary embodiment, a pressure-side partial flow is thus passively fanned out to the side in addition to the pressure-side fanning out of the fluid flow. The inner contour and profile variation 20 are preferably positioned in relation to each other in such a way that a wave crest of profile variation 20 is situated in the area of a wave trough of the inner contour and vice versa. Profile variation 20 and the inner contour preferably have an identical design.

FIG. 8 shows an example of an active wake mixture, in which the so-called “Coanda effect” is used. For this purpose, supporting ribs 14 each have at least one suction-side blow-out opening 22 in the area of their trailing edges 16 for blowing out a fluid into a profile-proximate boundary layer. Blow-out opening 22 is designed as a longitudinal slot or as a plurality of bore holes. It splits suction side 24 into a front suction-side section 40 and a rear suction-side section 28. A pressure-side section 30 has an invariable outflow area 38 and is extended in the manner of a bulge in the direction of suction side 24 in such a way that its extension forms suction-side section 28 having a concave, suction-side outflow area 36. Outflow area 36 is provided with an outer contour in such a way that the fluid flowing out of outlet opening 22 follows the outer contour over a profile-proximate area after it is detached from outflow area 34, which avoids cross flows in the profile-distant partial flow layers.

As shown in FIGS. 9 and 10, flow splitter blades or splitter blades 20 42 may be situated in a downstream or rear area of transition duct 1. Individual (FIG. 9) or multiple (FIG. 10) splitter blades 42 may be situated between supporting ribs 14 and also provided with an active and/or passive wake mixture 18 in the area of their trailing edges 16. Splitter blades 42 cause the flow to be split between supporting ribs 14 and help deflect flow 12 in the circumferential direction. Splitter blades 42 are shorter than supporting ribs 14 and have a wing profile which is significantly narrower than the profile of supporting ribs 14.

As indicated in the upper area of FIG. 9, three-dimensional, parasitic secondary flows 44 may form in the rear area of transition duct 1. These secondary flows 44 are induced by the two-fold deflection, namely the deflection radially to the outside, on the one hand, and the deflection in the circumferential direction, on the other hand, as well as the complex speed profile of flow 12. Secondary flows 22 44 may cause an unfavorable inflow to first moving blades 6 of low pressure turbine 4 and an excitation of moving blades 6. Due to the positioning of narrow splitter blades 42 between thicker supporting ribs 14, the generation of parasitic secondary flows 44 may be significantly reduced.

FIG. 10 shows the arrangement of two splitter blades 42 a, 42 b between adjacent supporting ribs 14. It is strived for that the highest possible share of the flow deflection is handled by splitter blades 42 (42 a, 42 b). The number of long and heavy supporting ribs 14 is essentially determined by the stability requirements and the number or cross section size of the supply lines accommodated in supporting ribs 14.

In other exemplary modifications, up to five splitter blades 42 may be situated between two supporting ribs 14. If necessary, more than five splitter blades 42 may also be situated between two supporting ribs 14.

Geometric sizes of supporting ribs 14 and splitter blades 42 a, 42 b are also indicated in FIG. 10. An axial installation depth of supporting ribs 14 is indicated by L_(ax), a profile chord length is indicated by L and a maximum profile thickness is indicated by D_(max). The corresponding nomenclatures may also be transferred to splitter blades 42 a, 42 b by the additional index “splitter.” An axial length or installation depth of transition duct 1 itself may be indicated by L_(ax, TMTF). Axial installation depth L_(ax, TMTF) of transition duct 1 may be equal to or defined by axial length or installation depth L_(ax) of supporting ribs 14.

In summary, features of supporting ribs 14 which may be combined with those of splitter blades 42 may be indicated as follows:

a) Deflecting supporting ribs 14 and thin splitter blades 42 are situated in tandem in the transition duct; b) Relative thickness d_(max, splitter)/L of splitter blades 42 is less than a limiting value

d _(max,splitter) /L<15%;

in particular

d _(max,splitter) /L<10%;

c) The axial installation depth of splitter blades 42 is

25%<L _(ax, splitter) /L _(ax, TMTF);

in particular

30%<L _(ax, splitter) /L _(ax, TMTF);

and/or

L _(ax, splitter) /L _(ax, TMTF)<100%;

d) Splitter blades 42 extend in an area which begins at 30% L_(ax, TMTF) minimum and ends at 125% L_(ax, TMTF) maximum in the axial direction. Splitter blades 42 are offset to the rear in relation to leading edges 46 of supporting ribs 14 in the flow direction and may project to the rear beyond trailing edges 16 of supporting ribs 14.

It has proven to be advantageous if divisions T₁ and T₂ are different in the case of one splitter blade 42 and if divisions T₁ through T₂ are different in the case of multiple splitter blades 42 a, etc. (with n−1 splitter blades). In this case, splitter chord lengths L_(splitter) may also be different.

Disclosed is a transition duct for a turbomachine, in particular an aircraft engine, for forming a flow channel between an upstream flow cross section and a downstream flow cross section, including supporting ribs which extend between a radially inner duct wall and a radially outer duct wall and each of which has a profile for deflecting a flow from an inlet area to an outlet area of the transition duct, the supporting ribs each having a profile variation in the area of their trailing edge and/or at least one blow-out opening for blowing out a fluid; also disclosed is a turbomachine having a transition duct of this type.

List Of Reference Numerals

1 transition duct 2 high pressure turbine 4 low pressure turbine 6 moving blade 8 inner duct wall 10 outer duct wall 12 flow 14 supporting rib 16 trailing edge 18 wake mixture 20 profile variation 22 blow-out opening 24 suction side 26 pressure side 27 auxiliary line 28 suction-side section 30 pressure-side section 32 suction-side slot area 34 pressure-side slot area 36 suction-side outflow area 38 pressure-side outflow area 40 suction-side section 42, 42 a, b flow splitter blade/splitter blade 44 secondary flow 46 leading edge α₁ flow angle, inlet flow α₂ flow angle, outlet flow Δα Flow deflection angle d_(max) Maximum profile thickness of the supporting ribs d_(max,Splitter) Maximum profile thickness of the splitter blades F₁ Inlet area at the beginning of the transition duct F₂ Outlet area at the end of the transition duct L Profile chord length of the supporting ribs L_(Splitter) Profile chord length of the splitter blades L_(ax) Axial installation depth of the supporting ribs L_(ax,Splitter) Axial installation depth of the splitter blades L_(ax,TMTF) Axial installation depth of the transition duct R Rotation axis/turbine axis T_(1 to n) Division (distance running perpendicularly to the rotation axis) between the outlet edges of the supporting ribs and the splitter blades U Rotation direction 

1-12. (canceled)
 13. A transition duct for a turbomachine for forming a flow channel between an upstream flow cross section and a downstream flow cross section, the transition duct comprising: a radially inner duct wall; a radially outer duct wall; and supporting ribs extending between the radially inner duct wall and the radially outer duct wall, each supporting rib having a profile for deflecting a flow from an inlet area to an outlet area of the transition duct, each supporting rib having a profile variation in an area of a trailing edge and/or at least one blow-out opening for blowing out a fluid.
 14. The transition duct as recited in claim 13 wherein the trailing edge is alternately offset in relation to a suction side and to a pressure side of the supporting rib.
 15. The transition duct as recited in claim 13 wherein the trailing edge has a wave design in the flow direction.
 16. The transition duct as recited in claim 13 wherein each supporting rib has the at least one blow-out opening exiting the trailing edge between a suction side and a pressure side of the supporting rib.
 17. The transition duct as recited in claim 16 wherein the at least one blow-out opening is a longitudinal slot extending from the inner duct wall to the outer duct wall, a suction-side slot area having a wave-shaped design and a diametrically opposed pressure-side slot area being designed without variation.
 18. The transition duct as recited in claim 17 wherein a suction-side outflow area diametrically opposed to the suction-side slot area has a further wave-shaped design.
 19. The transition duet as recited in claim 16 wherein the at least one blow-out opening is a longitudinal slot, a pressure-side slot area having a wave-shaped design and a diametrically opposed suction-side slot area being designed without variation.
 20. The transition duct as recited in claim 19 wherein a pressure-side outflow area diametrically opposed to the pressure-side slot area has a wave-shaped design.
 21. The transition duct as recited in claim 13 wherein the supporting rib has the blow-out opening exiting on a suction side.
 22. The transition duct as recited in claim 13 further comprising flow splitter blades situated between the supporting ribs and having a smaller relative profile thickness than the supporting ribs (14).
 23. The transition duct as recited in claim 22 wherein the flow splitter blades having a further trailing edge-side profile variation and/or at least one further blow-out opening.
 24. A turbomachine comprising a transition duct as recited claim
 13. 25. An aircraft engine comprising the turbomachine as recited in claim
 24. 